Transmission line network for radio receiving antennae



NOV. 19, 1935. w w c m 2,021,734

TRANSMISSION LINE NETWORK-FOR RADIO RECEIVING ANTENN/E Filed May 14,1932 23 FIG. I 28 J II I INVENTOR WILLIAM W. MACALPINE ATTORNE PatentedNov. 19, 1935 UNITED .STATES PATENT. or-Pics amass D10 RECEIVINGWllIiamW.llacalpino,East0n-nge.

lignortolnternational MWMNGIl-l'k;

New York The present invention relates to transmission lines andnetworks for interconnecting radio receivers and the antenna: supplyingenergy thereto.-

At the present time the receiving antenna for a radio receiver is placedas near the receiver as is plrvsicallypossible. This in many instancesmeans that the antenna. is placed in a location where the level ofinterfering signals is high and the reception consequently poor. Thisinvention makes it possible to locate the antenna at a point remote fromthe radio receiver and to transmit the signals received on that antennato the receiver without picking up extraneous noise.

One of the objects of this invention is the provision of means wherebyan antenna may be located ata point remote from the receiver in alocation where interfering signals are not pres-'- ent or are present toonly a slight degree.

Another object of the invention is to transmit,

received signals from a receiving antenna to a remote radio receiverwithout appreciable distortion.

A further object of the invention is to provide means whereby the inputenergy supplied to a receiver from a remote antenna is substantiallyunchanged in amount regardless of the frequency of the signals to whichthe receiver is tuned.

Further objects of the invention will appear from the followingdescription taken in connection with the drawing.

In the drawing:

Fig. 1 shows the antenna, transformer network, transmission line andreceiver, particularly designed and adapted for reception of signals inthe broadcast range, that is to say signals of frequencies ranging from600 to 1800 kilocycles.

Fig. 2 is similar to Fig. 1 except that the transformer network isadapted to thereception of signals in the short wave band, that isfrequencies from 1.5 to 20 megacycles.

Fig. 3 shows an arrangement for operation over a wider frequency handthan the arrangement of Figs. 1 and 2. I

Fig. 4 shows a modified arrangement of the receiver input transformersadapted to feed two receivers from a single transmission line when thosereceivers are operating over different frequency ranges.

Fig. 5 shows an arrangement for operating a number of receivers from thesame tron line and antenna.

7 Referring to Fig'. 1 the receiving antenna designated HI, has inseries herewith the two tuned circuits II and lljcrmnected inseriesopposition between the antenna and ground. Tuned circuit ll comprises aninductance coil It and condenser i4 and similarly, tuned circuit i2comprises the coil II and condenser-ll.- Coils I3 and I! are closelycoupled and form the primaries of a transformer network, the secondarim,of which are designated, respectively, I! and 20; Tunedcircuit II istuned to a frequency near the upper end and within the broadcast band.that is to a frequency of about 1500 kilocycles.

Tuned circuit l2 has a resonant frequency near the lower end of andwithin the broadcast band,

that is about 600 kilocycles. The coils I9 and to the transmission line2|. The capacity shield 22 is inserted between the primaries and sec- 1ondaries of thecoils and is grounded at 23. It

is apparent from the above that there is close 20 coupling betweenprimary l8. and secondary l9 and between primary l1 and secondary 20.Sec- 7 ondary II is smaller than secondary 20, and this together withthe fact that condenser 24 is in series with secondary i9, serves toprevent the g shortcircuiting of coil 20 at the low frequencies,

while at the high frequencies, coil 20 being larger has little effect onsignals in coil i9. At frequencies between the resonant peaks mentioned,namely 1500 and 600 kilocycles, and to some 30 extent at allfrequencies, energy is transferred from the antenna to the line throughboth l3l9 and "-20. It is to be noted that while coils l3 and II areconnected in'series opposition, coils I9 and 20 are connected inparallel aiding 5 relation.

The transmission line, designated 2|, connects to the secondaries i9 and-20 and extends to the desired position of the radio receiver at whichpoint it terminates in the primary 26 of 'trans- 40 former 25. Thecenter points of secondary 20 and of primary 26 are connected to groundto equalize and cancel out extraneous capacitive and inductive effectson the line. The transformer 25 has a capacity shield 28 between its 45windings 26 and 21. Secondary winding 21 is connected to the signalinput circuit of the receiver. The transformer design is such that theimpedance of the receiver matches the impedance of the line, thereceiver impedance considered tocoil II and coil ll tocoil 20.Inpractice this close coupling is accomplished, in the case of coils l3and l9, l1 and II by winding coils l8 and 2| side by side upon the sameform after which a sheet of foil shielding material is wrapped aboutthese coils, the foil being insulated by suitable paper insulation in awell known manner. Coils II and I! are then wound above their respectivesecondaries I! and 2.. Transformer 2! is constructed in the same manner,this transformer however having but two coils 2i and 21, wound one abovethe other with paper and foil between.

The constants of the transformer network are so chosen that the input tothe receiver is substantially the same at all frequencies. The mode ofconnecting coils i3, i1, is and III is such that the currents in thetransmission line are additive in phase. This serves to eliminate theregions of very low energy transfer which would occur if the currentswere out of phase.

Fig. 2 shows an arrangement for shortwave operation. In this instance ithas been found unnecessary to supply two secondary windings. Hence thesecondaries is and 20 of Fig. 1 are replaced by a single center tappedsecondary 30. Condenser 29 may be omitted in this arrangement, since atthese high frequencies the capacity of the antenna to ground shown indotted lines -at 32 suffices, together with coil 33, to form a resonantcircuit at the higher frequencies of the band. The operation of thiscircuit is exactly similar to that described above in connection withFig. 1.

Fig. 3 shows an alternative transformer network for covering a widerfrequency band than that for which the above described arrangements aresuitable. In this arrangement there are three tuned circuits one ofwhich is tuned to a frequency near the upper limit of the band to bereceived, the second to a frequency near the middle of the band and thethird to a frequency near the lower limit of the band. The receiverinput transformer may be of the form described in connection with Figs.1 and 2 or of the alternative form described below. The condenser totune the high frequency coil may be omitted in some cases.

Fig. 4 shows an alternative arrangement of the transmission line andreceiver input transform-v ers. This arrangement is adapted for use whenthe two receivers are operating on different frequency bands. Itcomprises two transformer primaries connected in parallel to the line,with a blocking condenser connected in series with one winding of one ofthe transformers. This condenser servos mainly to prevent thistransformer primary, whichis adapted to transmit high frequencies, fromacting-as a short circuit around the other parallel transformer primary.

Fig. 5 shows a transmission line along which several receiving sets arelocated. These receiving sets are connected to the transmission line bytransformers similar in every respect to transformer of Fig. 1. In thiscase it is however desirable that the resultant of the impedances of theseveral receiving sets be approximately equal to the line impedance.

The transmission line proper may be of any one of several forms astwisted pair wire, sheathed wires, 9. transposed pair or in some casesparallel open wires. The particular form of the transmission line formsno'part of the invention and is shown merely for clarity.

The foregoing is given for the purpose ofdescriptiononly,andisinnowaytolimittlie scope of the appended claims.

What is claimed is:

1. In a on line system for frequencies within a band of frequencies, anantenna, 5

a radio receiver, a pair of transformer primary windings in seriesopposing relation connected to said antenna to receive energy therefrom,a tuning condenser in shunt to each primary winding whereby the windingsare tuned to different freo quencies within said band, secondarywindings inductively coupled to said primary windings, a transmissionline connected to said secondary windings to receive energy of allfrequencies within said band, and means for coupling said trans- 15mission line to said radio receiver.

2. In a transmission line system for frequencies within a band offrequencies, an antenna, a radio receiver, a pair of transformerwindings in series opposing relationship connected to said go antenna toreceive energy therefrom, a tuning condenser in shunt to each of saidwindings whereby the windings are tuned to different frequencies withinsaid band, a secondary winding coupled to said first mentioned windingsto re- 25 ceive therefrom energy of all frequencies within said band, atransmission line connected to said secondary winding, and means forcoupling said transmission line to said radio receiver.

3. In a transmission line system for frequencies within a band offrequencies, a receiving antenna, a transmission line receiving energytherefrom, a doubly resonant circuit connected in series with saidantenna and comprising trans-- former primary windings connected inseries opposing relation, said windings being tuned to differentfrequencies within said band, and means for transferring energy of allfrequencies within said band from said doubly resonant circuit to saidtransmission line, said means comprising 40 transformer secondarywindings connected in parallel aiding relationship.

4. A receiving system for frequencies within the broadcast rangecomprising a radio broadcast receiver, an antenna for supplying energythereto, a transmission line coupled to said radio receiver, means formatching the impedance of said receiver with the impedance of said line,a circuit resonant to a frequency near the upper and to a frequency nearthe lower limit of the broadcast range connected to said antenna, saidcircuit containing two inductances in opposing relation, and means forcoupling said resonant circuit to said transmission line so as totransfer thereto energy of all frequencies within said band. 5

5. A receiving system for frequencies within a band of frequenciescomprising a radio receiver, impedance matching means, a transmissionline coupled to said radio receiver thru said impedance matching means,a tuned network 0 coupled to said transmission line and comprising aplurality of transformer windings each connected in series opposingrelationship to the preceding windings, the windings being tuned todifferent frequencies within said band, whereby 5 energy of allfrequencies within said band is transferred to said transmission lineand an antenna circuit connected with said network.

6. A receiving system for frequencies within a band of frequenciescomprising a receiving an- 7 tenna circuit, a plurality of tunedoscillation circuits having coupled inductances in seriesopposingrelation connected in said antenna circuit, said oscillation circuitsbeing tuned to different frequencies within said band, a transmissionline,

and means comprising secondary inductances connected to said line inparallel aiding relationship to each other for transferring energy ofall frequencies within said band from said tuned circuit inductances tosaid line.

7. A transformer network for interconnecting a receiving antenna and atransmission line comprising a pair of opposed inductances connected inseries with said antenna, means to tune one of said inductances to afrequency near the upper end of a band of frequencies to be received,means to tune the other of said inductances to a frequency near thelowerend of a band of frequencies to be received, and a plurality ofmeans connected in parallel for coupling said inductances to saidtransmission line so as to transmit thereto energy of all frequencieswithin said band.

8. A transformer network for interconnecting a receiving antenna and atransmission line comprising a pair of opposed inductances connected inseries with said antenna, means to time one of said inductances to afrequency near the upper end of a band of frequencies to be received,means to tune the other of said induetances to a frequency near thelower end of a band of frequencies to be received, and means forcoupling said inductances to said transmission line.

said primary windings to receive therefrom energy of all frequencieswithin a band including said different frequencies, means for connectingsaid secondary windings in parallel to said transmission line, and acondenser in series with one of said secondary windings only.

10. A network for coupling an antenna circuit to a transmission line andcomprising a plurality of tuned oscillation circuits having coupledinductances in series opposing relation for connection to said antennacircuit, each oscillation circuit being tuned to a different frequencywithin a band of frequencies and one of said oscillation circuits beingtuned to a frequency near the upper limit and another to a frequencynear the lower limit of said band, and means comprising secondaryinductances connectable to said line in parallel aiding relationship toeach other for transferring energy of all frequencies within said bandfrom said tuned circuit inductances to said line.

11. A network for coupling an antenna circuit to a ton line comprising aplurality of tuned oscillation circuits having coupled inductances inseries opposing relation for connection to said antenna circuit, eachoscillation circuit being tuned to a different frequency within a bandof frequencies and one of said oscillation 5 circuits being tuned to afrequency near the upper limit and another to a frequency near the lowerlimit of said band, and means comprising a secondary inductance coupledto said tuned oscillation circuits to 'receive therefrom energy of allfrequencies within said band and connectable to said transmission lineto transfer said energy thereto.

12. A network for coupling an antenna circuit 1 to a transmission linecomprising two tuned oscillation circuits having coupled inductances inopposing relation for connection to said antenna circuit, oneoscillation circuit being tuned to a A frequency near the upper limit ofa band of frequencies to be received and the other being tuned to afrequency near the lower limit of said band, and a secondary-inductancecoupled to said oscillation circuit inductances to receive therefromenergy of all frequencies within said band and connectable to saidtransmission line for trans-- ferring said energy thereto.

13. A network for coupling an antenna circuit to a transmission linecomprising two tuned oscillation circuits having coupled inductances inopposing relation for connection to said antenna circuit, oneoscillation circuit being tuned to a frequency near the upper limit of aband of frequencies to be received and the other being tuned to afrequency near the lower limit of said band, and two secondaryinductances coupled to 85 said oscillation circuit inductances toreceive therefrom energy of all frequencis within said band, saidsecondary inductances being connectable in parallel aiding relationshipto said transmission line, one of said secondary inductances beingsmaller than the other, and a condenser connected in series with thesmaller of said secondary inductances.

14. A network for coupling an antenna circuit to a transmission line soas to transfer from the former to the latter energy of all frequencieswithin a band of frequencies and comprising a plurality of tunedoscillation circuits having coupled inductances connected in opposingrelation in said antenna circuit, each oscillation circuit being tunedto a different frequency within said band and one of said oscillationcircuits being tuned to a frequency near the upper limit and anotherthereof to a frequency near the lower limit of saidband, and a secondaryinductance coupled to said oscillation circuit inductances andconnectable to said transmission line.

WILLIAM W. MACALPINE.

